Correlation between hyperinflation defined as an elevated RV/TLC ratio and body composition and cytokine profile in patients with chronic obstructive pulmonary disease.

Introduction: Body composition is an important prognostic factor in patients with COPD. The decrease in fat free mass (FFM), muscle mass (MM) and increase in visceral fat is associated with an elevated secretion of cytokines which promote systemic inflammation. The aim of the study was to evaluate body composition and the cytokine profile in patients with COPD in relation with the presence of hyperinflation.

Material and methods: The study group consisted of 149 patients (61F, 88M) with stable COPD in all stages of severity aged 68 ± 8.8 yrs. All the patients underwent spirometry and bodypletysmography with bronchial reversibility testing. Hyperinflation was defined as RV%TLC > 48% and > 126% predicted. Body composition was analyzed by bioimpedance. The following serum inflammatory markers were evaluated: C-reactive protein, IL-6, IL-8, TNF-a, CC16, adiponectin and resistin.

Results: Hyperinflation was found in 96 patients (group A) and it was more frequent in women than men (49/61 vs. 47/88, p < 0.001). BMI and age in this group were comparable to those in patients without hyperinflation (group B). Patients with hyperinflation have lover FFM, FFM index, MM and MM index and total body water and higher fat mass and fat mass index. We found significantly higher serum concentrations of inflammatory markers in group A: IL-6 - 6.4 ± 10.9 vs. 3.6 ± 4.2 pg/ml, resistin - 9.3 ± 4.2 vs. 7.6 ± 2.4 ng/ml, CRP 4.1 ± 2.3 vs. 2.9±2.1 mg/l, respectively.

Conclusions: Patients with hyperinflation have a lower FFMI, TBW and MMI and a higher proportion of fat tissue. Hyperinflation is associated with elevated concentrations of inflammatory markers what may be associated with more severe disease. Body compositions abnormality and higher activity of systemic inflammation could therefore be a negative prognostic factor in COPD patients.